IDK......where to go from here. Poor idle quality... still some diff on cyl drop test

[MACH1SCJ]

I have checked, checked, checked & tripple checked again....decarboned,

Carbs are clean! Or I cant find anything wrong with them,

Spark is a bright blue core @ 1/2" gap.

Compression hot is 130 & 135

Leakdown hot 20%-22% both cylinders

I adjusted the carbs by rpm. Then I hooked up my Vantage multimeter with Kv module. The signal from the ign module looks good & even on both cylinders. I then fine tuned the carbs to match peak spark Kv for each cylinder, Which is around 5Kv. ( smoothest/highest idle matched, they all lined up tegother)

The top cylinder firing line as not as stable as the lower cylinder. Looks Like there is inconsistat fuel mixture in the combustion chamber. I was thinking maybe a crankcase leak but I have gone all around with propane & have no response from the engine. Even flooded under the flywheel with propane & still no change.

I still have a different sound from each carb at idle. Just off idle engine smoothes out & the carbs have harmony in their sound. The lower plug shows more burnt oil on it then the top plug. The top cylinder looks to have more unburnt oil in it.

I have confirmed the top cylinder not producing power randomly. It is dropping maybe 1 out of 8 or 10 power pluses

I am ready to give up on this problem & just run it the way it is. but I do not want to cause damage.

What are your thoughts?

 

[Daviet]

Re: IDK......where to go from here. Poor idle quality... still some diff on cyl drop

What are you working on?

 

[MACH1SCJ]

Re: IDK......where to go from here. Poor idle quality... still some diff on cyl drop

What are you working on?

Sorry, I just remebered I did not state that info.

Engine is a 1990 Rude 48 spl 2 cylinder model E48ESLESA

Fresh fuel 50:1 I took a sample today & need to double check it now that it has been sitting for a few hrs.

 

[Daviet]

Re: IDK......where to go from here. Poor idle quality... still some diff on cyl drop

Does your fuel pump mount to the upper cylinder, maybe you have a leaking diaphram allowing excess fuel into the upper cylinder.

 

[MACH1SCJ]

Re: IDK......where to go from here. Poor idle quality... still some diff on cyl drop

It does & it is brand new, but I have not rechecked that yet......

 

[MACH1SCJ]

Re: IDK......where to go from here. Poor idle quality... still some diff on cyl drop

Does your fuel pump mount to the upper cylinder, maybe you have a leaking diaphram allowing excess fuel into the upper cylinder.

Hot damn!!! You are the MAN!!! Another case of a "Brand New Not Known Good Part"

There should be NO fuel at all in the signal hole, correct?

I pinched off the fuel line from the pump & held light presure on the primer bulb & could see fuel build up in the signal port of the fuel pump. It was not much but was enough to turn over & wet the end of my finger.

Do I try to get it warrantied or do I take two to make one???

Think something caused this new evinrude pump to fail on the madien voyage or just a defective part?

 

[boobie]

Re: IDK......where to go from here. Poor idle quality... still some diff on cyl drop

Take it back for warranty. There are new parts and good parts.

 

[Daviet]

Re: IDK......where to go from here. Poor idle quality... still some diff on cyl drop

As boobie said, take it back and get another pump. Let us know how it runs with a new pump.

 

[MACH1SCJ]

Re: IDK......where to go from here. Poor idle quality... still some diff on cyl drop

I ordered it off internet. It states to take to a dealer for verification of failure, & the closest dealer is not open till monday. I will post when when I have an update.

 

[MACH1SCJ]

Re: IDK......where to go from here. Poor idle quality... still some diff on cyl drop

I still have not gotten the pump warrantied yet, susposed to be on order & should have arrived thursday but "ups did not show up".
So I found a cap to replace the one the PO cracked be incorrect repairs & a used gasket from a local boat repair shop. & spent 12 hrs on the water today. I need to retune the carbs & relink-n-sync again on the water. But WOW what a difference, at least I feel like I know the engine very well now. I want it to idle just a little bit smoother but the idle in gear on the water is only around 600 rpm & is pretty dog gone good now. Thanks for all of the help everyone.